A conventional portable computer can be used in many places with its in-built power source without the need for attachment to an external power source. In some of the places where a portable computer can be used, there is a low ambient light level. Examples of such environments having low ambient light levels include conference rooms during presentations, on aircraft or in cars. In areas where there is a low ambient light level, the display may be clearly seen as the display on a portable computer is typically backlit. However, the keyboard and the individual keys making up the keyboard may not be able to be seen in such conditions.
There have been previous attempts to provide lit keyboards including the provision of a light to illuminate the keyboard and the use of fluorescent materials applied to the keys. The provision of a separate light suffers from the disadvantage that additional power is needed for the light and so the usage time of the portable computer between recharges from the external power source is reduced. The provision of fluorescent materials on the keys requires that the materials are “charged” by being illuminated for a period of time prior to use. Since a portable computer is typically closed when not in use, the recharging cannot be readily achieved by normal ambient light.
PCT Patent Application WO97/04437 discloses a portable computer having a keyboard which is lit for use in low ambient light locations. Two embodiments are disclosed, one in which light from the backlight of the display panel is routed via a light pipe coupler and a backlight panel into a hollow portion of the key and one in which a portion of the light from the display panel backlight is reflected onto the top of the key making up the keyboard. The light from the backlight is coupled through a light pipe coupler, which may restrict the angle of use of the display panel with respect to the keyboard. A gate is provided to restrict or prevent light from entering the backlight panel. The light from the backlight is always white and so the key illumination will also always be white.
So it would be desirable to provide an improved mechanism for directing light from a display backlight to keys in a portable computer. It would also be desirable to provide an improved mechanism for controlling the intensity of lighting and the color of lighting for the keys in a portable computer.